1. Field of the Invention
The invention relates to a band-gap reference voltage source comprising a first current branch including a first field effect transistor; a second current branch including a second field effect transistor; a reference resistor arranged in series with one of the field effect transistors; and means for producing different current densities in the first and in the second field effect transistor.
2. Description of Related Art
Such a band-gap reference voltage source is known from the publication: "A Low-Voltage CMOS Bandgap Reference", IEEE Journal of Solid-State Circuits, Vol. SC-14, No. 3, June 1979. Said publication describes a band-gap reference voltage source comprising MOS transistors. The current which flows through the MOS transistors is then so small that the MOS transistors are in the weak inversion mode, as a result of which the MOS transistors exhibit characteristics which are highly equivalent to those of bipolar transistors. Thus, it possible to use MOS transistors in order to make a band-gap reference voltage source whose circuit diagram corresponds to those of well-known band-gap reference voltage sources using bipolar transistors.
A drawback of the known band-gap reference voltage source is that it supplies an output voltage which is not low enough for some uses.